Fast C++ matrix library with easy to use functions and syntax, deliberately similar to Matlab. Uses template meta-programming techniques.
Also provides efficient wrappers for LAPACK, BLAS and ATLAS libraries, including high-performance versions such as Intel MKL, AMD ACML and OpenBLAS.
For more details, see http://arma.sourceforge.net

X Certificate and Key management is an interface for managing asymetric keys like RSA or DSA. It is intended as a small CA for creation and signing certificates. It uses the OpenSSL library for the cryptographic operations.

The Sleuth Kit is a C++ library and collection of open source file system forensics tools that allow you to, among other things, view allocated and deleted data from NTFS, FAT, FFS, EXT2, Ext3, HFS+, and ISO9660 images.

Safe Exam Browser is a webbrowser-environment to carry out online-exams safely. The software changes any computer into a secure workstation. It regulates the access to any utilities and prevents students from using unauthorised resources.

reacTIVision is a computer vision framework for the fast and robust tracking of markers attached on physical objects, and the creation of multi-touch surfaces. It was designed for the rapid development of table-based tangible user interfaces.